A number of other compounds also are capable of reducing cupric ions to cuprous ions and can cause false-positives.

Ambient transport temperatures result in growth of bacteria. Bacteria consume reducing substances, which can result in false-negative results, so ambient specimens are rejected.

This test has poor sensitivity for oligosaccharides and poor sensitivity from diaper stools because fluid is reabsorbed into the diaper. Testing of only the solid portion of the stool will give a falsely-low reading since the liquid portion of the stool contains the water-soluble sugars.